Well, it's a bit more than penis jokes. It does mock homophobia somewhat (the fight at the end is absolutely the most hilarious thing I've ever seen Sacha Baron Cohen do).
He was good as long as he kept to his Ali G shows, where borat and bruno made an appearance now and then. Eps back then were genuinely funny. Turning them all into a movie was not a great idea, but I'm sure it earned him a lot of $$$...